Hydrogenative thermal cracking

ABSTRACT

Activated hydrogen is prepared by contacting molecular hydrogen with a metal phthalocyanine catalyst. A heavy hydrocarbonaceous charge stock is then reacted with the activated hydrogen at hydrogenative thermal cracking conditions including a maximum temperature in the range of 500* F. to about 800* F.

United States Patent [1 1 Stolfa HYDROGENATIVE THERMAL CRACKING [75] Inventor: Frank Stolfa, Park Ridge, Ill. 9

[73] Assignee: Universal Oil Products Company,

Des Plaines, Ill.

221 Filed: Jan. 14,1971

211 Appl. No.: 106,516

[52] US. Cl 208/107, 208/108 [51] Int. Cl Cl0g 13/02 [58] Field of Search 208/107, 108

[56] References Cited UNITED STATES PATENTS R18,318 1/1932 Frankfurter 208/107 X 1,857,814 10/1932 Krauch et al. 208/107 X 2,046,749 7/1936 Isom 208/107 X 2,088,214 7/1937 208/107 X 3,502,571 3/1970 Stolfa 208/107 UX OTHER PUBLICATIONS Moser et al., Phthalocyanine Compounds, Reinhold Nov. 20, 1973 Publishing Corp., N.Y. (1963), pps. 61-67. Copy in library.

KirkOthrner, Encyclopedia of Chemical Technology, 11, 2nd ed., Interscience Publishers, N.Y. 1966, pps. 345-346. Copy in library. 1

Primary Examiner-Daniel E. Wyman Assistant Examine rPaul F. Shaver AttorneyJames R. Hoatson, Jr. and Robert W.

Erickson [57] ABSTRACT 4 Claims, 2 Drawing Figures PATENTEU NOV 2 0 I975 SHEET 10F 2 ua ox mmmox b $793 ATTORNEYS HYDROGENATIVE THERMAL CRACKING APPLICABILITY OF INVENTION The invention herein described is adaptable to a process for the conversion of hydrocarbonaceous charge stocks, and, in particular, those charge stocks broadly categorized in the art as black oils". More specifically, my invention is intended for use in effecting the hydrogenative thermal cracking of heavy hydrocarbonaceous feed stocks. Atmospheric tower bottoms products, vacuum tower bottoms products, crude oil residuum, coal oil extracts, topped crude oils and tar sand oil extracts, etc., are illustrative, but not limiting, of those black oils which can be subjected to hydrogenative thermal cracking in accordance with the present invention.

Black oils contain exceedingly large amounts of high molecular weight sulfurous and nitrogenous compounds. In addition, these heavy hydrocarbonaceous mixtures contain significant quantities of hydrocarboninsoluble asphaltics and organo-metallic compounds principally comprising iron, nickel and vanadium. Currently, an abundant supply of such material exists, most of which has a gravity less than about 20.0 API and a boiling range which indicates that 10.0 percent by volume, or more, boils above a temperatureof l,050 F. The abundant supply virtually demands conversion to satisfy the steadily increasing need for lower-boiling hydrocarbon products. Illustrative of those charge stocks above described, is a vacuum residuum having a gravity of about 8.8 AP], an initial boiling point (ASTM D- 1 160) of 690 F. and a 20.0 percent volumetric distillation feiripe raturc of i355 F; and containing 3.0 percent by weight of sulfurous compounds, as sulfur, 4,300 ppm. by weight of nitrogen, 6.5 percent by weight of insoluble asphaltics and about 100 ppm. of total metals.

The principal difficulty, accompanying the conversion of black oils, stems from the presence of asphaltic material and the organo-metallic complexes. Fixed-bed catalytic processes, although advantageously used in a myriad of hydrocarbon conversion processes, are unsuited for use in black oil processing due to the rapid deposition of coke onto the catalytic composite, and the extremely short period of successful on-stream operation until the catalyst picks up metal contaminants equal to its own weight. Thermal cracking, with or without the presence of molecular hydrogen, suffers particularly from the fact the the required high temperatures i.e., 850 F. to l,250 F. foster excessive coke laydown in the thermal coil and the miscellaneous hardware appurtenant thereto. Many described techniques favor a slurry-type operation wherein a solid catalyst, in finely-divided form, is intimately admixed with the charge, the resulting slurry being brought'to reaction conditions in a suitable reaction chamber. Such techniques incur great expense in the recovery of spent and carbonized catalyst from the reaction chamber effluent, accompanied by extensive regeneration facilities required to permit re-use of the catalyst.

OBJECTS AND EMBODIMENTS A principal object of the present invention is to avoid the difficulties encountered in present-day black oil processes. A corollary objective is to provide an improved hydrogenative thermal cracking process.

Another object of my invention involves the use of a catalyst while effecting hydrogenative thermal cracking in a manner such that the charge stockdoes not contact such catalyst. v

The objects are accomplished through the utilization of one embodiment which encompasses a process for the hydrogenative thermal cracking of the hydrocarbonaceous charge stock, which process comprises contacting molecular hydrogen with a metal phthalocyanine catalyst at conditions selected to produce activated hydrogen and reacting said charge'stock with said activated hydrogen at thermal cracking conditions.

Other embodiments of my invention are concerned with preferred metal phthalocyanines and operating conditions. These, as well as other objects, will become evident, to those having expertise in the art, from the following more detailed description.

PRIOR ART Candor compels recognition of the fact that thermal cracking is one of the oldest conversion processes known in the art. Indeed, hydrogenative thermal cracking is thoroughly described in published literature, including those processes which practice the cojoint use of an hydrogen donor diluent i.e., polycyclic hydrocarbons. Significantly none of these processes recognize the utilization of activated hydrogen, nor the present means of integrating the method of preparing such hydrogen with its use.

scribed an" impra'vea" mfiyiiype'iibeafutmzm the highly thermally stable metal phthalocyanine compounds as a finely divided catalyst. While offering a significant improvement, there continues to exist the necessity of recovering the metal phthalocyanine from the heavy residuum for re-use in the process. It should benoted that, in this process, the catalyst is being contacted by the charge stock, and is, therefore, subject to coke deposition. A

Reference is made to the existence of metal phthalocyanines from all eight Groups of the Period Table, Phthalocyanine Compounds"M0ser and Thomas, R'einholdt Publishing Company, page 105, 1963, with the preferred metal phthalocyanines being those which are thermally stable at elevated temperatures. Also indicated, is the effect of metal phthalocyanines as catalysts, pp. 61-67, and especially with respect to the activation of molecular hydrogen. There is, however, no recognition of the activation of hydrogen being integrated into a hydrogenative thermal cracking process in accordance with the present invention.

SUMMARY OF INVENTION An essential element of the present invention is the use of activated hydrogen for effecting the hydrogenative thermal cracking of hydrocarbonaceous charge stocks. This concept is based upon the effect of the necessary high temperature employed in thermal cracking. A portion of the compounds disassociated to form free radicals as below, for example:

(l) The highly reactive radicals do not appear in the ther mally cracked product effluent, but, depending upon size and the environment, (1) react with other hydrocarbons, (2) decompose to olefins and smaller radicals, or (3) combine with other radicals.

1 general, the smaller radicals, I-I-CI-I and C I-I -are more stable than larger radicals, and will more readily react with other hydrocarbons by capturing a hydrogen atom. Thus: 1

Larger radicals are unstable, and decompose to form olefins and smaller radicals, such as:

These free radical chain reactions are terminated when two radicals combine:

By initially supplying the more stable radicals, CH 'C I-I and especially I-l-a' greater degree of conversion is effected, a more saturated product results and, or greater significance, the cracking reactions can be effected at a temperature level much below that which heretofore had been considered necessary for thermal cracking, with or without molecular hydrogen. As hereinbefore stated, thermal cracking processes are generally effected at maximum temperatures ranging from 850 F. to as high as l,250 F. Through the use of the present process, the reaction takes place at lower maximum temperatures in the range of 500 F. to 800 F. To those having the requisite degree of skill in hydrocarbon conversion art, the immediate benefit will be recognized as being the virtually complete elimination of coke laydown;

Since the metal phthalocyanine catalyst does not contact the charge stock, but is employed for the sole purpose of providing the activated hydrogen, there is no contamination thereof through coke or metal deposition. Preferred metal phthalocyanines are those 'containing copper, beryllium, barium, titanium, tin, hafnium, vanadium, antimony, chromium, molybdenum, iron, cobalt, nickel, platinum and palladium, with copper, chromium, iron and cobalt being particularly preferred.

The metal phthalocyanines are solids, normally in powdered form, and may be pilled as such, or impregnated on an inorganic oxide carrier material. Various inorganic oxide carriers are well defined and thoroughly described in the prior art, and detailed discussion is not necessary herein. In any event, the phthalocyanine catalyst is disposed in the core of an annular reaction zone. The core is perforated, or is a permeable material, such as sintered metal, to permit the passage of activated hydrogen into the annular spaceas it is formed; the perforations are sized to prevent catalyst particles from passing into the annular space. The charge stock is introduced into the annular space to contact the activated hydrogen and react therewith. In order to prevent the charge stock from backflowing into the catalyst-containing core, the latter is maintained at a higher pressure than the annular space. A pressure differntial not less than about 5 psig. should be maintained. Since the charge is prevented from coming into contact with the phthalocyanine catalyst, the latter will not be consumed, will not suffer degradation from coke or metal deposition and will not have to be separated from the reaction product efi'luent. The perforated core is maintained under an imposed pressure in the range of about 1,000 to 3,000 psig., with the pressure differential controlled at a level of from 5 to about psig.

The molecular hydrogen is heated to a temperature in the range of 850 F. to 1,l50 F., and preferably at some intermediate level from 900 F. to l,000 F. The charge stock is separately heated to a level such that the maximum temperature in the annulus of the reaction zone is 500 F. to 800 R, which range, as will immediately be recognized, is much lower than generally considered necessary for thermal cracking operations. Molecular hydrogen is introduced into the core at a rate of from 3,000 to 30,000 scf./Bbl. of fresh feed charge stock, while the rate of the latter results in a liquid hourly space velocity of from 0.25 to 5.0.

The product effluent is utilized as a heat-exchange medium and subsequently further cooled and condensed to a temperature from 60 F.-to about F., prior to being introduced into a cold separator from which a hydrogenqich recycle stream is withdrawn. Normally liquid effluent is introduced into suitable fractionation/distillation facilities for recovery of the desired product slate. An unreacted asphaltic sludge is generally removed from the process, while at least a portion of the heavy gas oil is preferably recycled to the annular reaction zone to serve as a charge stock diluent.

Metal phthalocyanines appear to have the ability to produce CH and C ll; from methane and ethane, in addition to converting molecular hydrogen into the activated form. Since these free radicals can react as hereinabove set forth, as additional benefit resides in the elimination of a considerable portion of the facilities otherwise required to increase the purity of the hydrogen rich recycled gas stream.

DESCRIPTION OF DRAWINGS In further describing the present invention, reference will be made to the accompanying drawings which are presented for the sole purpose of illustration. Thus, miscellaneous appurtenances, including valves, controls, instrumenets, compressors, pumps, heatexchangers, start-up lines and heat-recovery circuits, etc., have been eliminated. The use of this type of conventional hardware is well within the purview of those skilled in the techniques of petroleum refining processing techniques.

FIG. 1 is representative of a simplified schematic flow diagram, while FIG. 2 is an enlarged view of the annular reaction zone.

With reference now to FIG. 1, the black oil charge stock, following heat-exchange with hot effluent, which technique is not illustrated, is introduced through line 1 intoheater 2. The temperature is raised to a level such that the maximum temperature in the annular space 5 of reaction zone' is 750 F. Heated charge is passed by way of line 3 into reaction zone 4, entering into annular space 5 under a pressure of about 2,050

psig. and at a liquid hourly space velocity of about 0.6.

Hydrogen is introduced, via line 6, and includes make-up hydrogen from line 7, into heater 14 wherein the temperature is increased to 950 F. The heated hydrogen stream passes through line 8 into catalystcontaining core 9 under a pressure of about 2,100 psig. Core 9 contains a copper phthalocyanine catalyst which produces activated hydrogen, CH and C l-l which pass through perforations 10 into annulus 5 to react with the charge stock therein.

The cracked product effluent is withdrawn by way of line 1 l and, following cooling and condensing to a temperature of about 1 10 F., is introduced into cold separator 12. A hydrogen-righ gaseous phase, containing methane, ethane and some propane, is removed via line 6 and recycled therethrough into heater 17. For the purposes of pressure control, a portion of the recycle gas is generally vented from the process. Normally liquid product effluent is sent by way of line 13 to suitable separation facilities for the removal of dissolved gaseous components i.e., propane and lighter and for the rejection of ametal-containing, unreacted asphaltic pitch.

FIG. 2 is an enlarged partial section of annular reactor 4 having an inner core 9 and an annular space 5. The molecular hydrogen enters via feed port 14, and is converted into activated hydrogen by contact with the copper phthalocyanine catalyst disposed in core 9. The activated hydrogen passes through perforations 10 into annular space 5. The charge stock enters through inlet port 15 and the cracked product effluent is withdrawn through outlet port 16.

Of necessity, the perforations are minute in size in order to prevent catalyst from entering annular space 5 and-to enable pressure differential control such that the charge stock does not come into contact with the copper phthalocyanine catalyst. in this regard, core 9 may be a permeable material, such as a sintered metal, or membrane, which, at a pressure differential of 5 to 100 psig, will permit diffuson of the activated hydrogen, but not the charge stock.

The foregoing illustrates the method by which my invention is illustrated, Other advantages and benefits will become apparent to those skilled in the art.

I claim as my invention:

1. A process for the hydrogenative thermal cracking ofa hydrocarbonaceous charge stock which comprises:

introducing said charge stock into a reaction zone maintained under superatmospheric pressure;

maintaining within said reaction zone a mass of copper phthalocyanine catalyst disposed in a hollow core having a wall formed of a gas permeable material;

introducing molecular hydrogen into said core and therein contacting it with said catalyst at conditions selected to produce activated hydrogen and including a pressure higher than said first mentioned pressure to preclude said charge stock from contacting the catalyst; and

flowing the resultant activated hydrogen through said gas permeable wall into said reaction zone and reacting said charge stock therewith at thermal cracking conditions.

2. The process of claim 1 further characterized in that cracked product effluent is withdrawn from said reaction zone and is separated into a hydrogen-rich gaseous phase containing methane and ethane, and a liquid product phase, and at least an aliquot portion of said hydrogen-rich gaseous phase is recycled to said catalyst-containing core.

3. A process for the hydrogenative thermal cracking of a hydrocarbonaceous charge stock which comprises:

introducing said charge stock into an annular reaction zone defined by an outer wall and a below specified inner core maintained under superatmospheric pressure;

maintaining within said reaction zone a mass of copper phthalocyanine catalyst disposed in a hollow core having a perforated wall;

introducing molecular hydrogen into said core and therein contacting it with said catalyst at conditions selected to produce activated hydrogen and including a pressure of 1,000 to 3,000 psig and higher than said first mentioned pressure to preclude said charge stock from contacting the catalyst; and flowing the resultant activated hydrogen through said perforated wall into said reaction zone and reacting said charge stock therewith at thermal cracking conditions, including a temperature of 500 F. to 800 F.

4. The process of claim 13 further characterized in that the conditions selected to produce activated hydrogen include a temperature above about 800 F.

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2. The process of claim 1 further characterized in that cracked product effluent is withdrawn from said reaction zone and is separated into a hydrogen-rich gaseous phase containing methane and ethane, and a liquid product phase, and at least an aliquot portion of said hydrogen-rich gaseous phase is recycled to said catalyst-containing core.
 3. A process for the hydrogenative thermal cracking of a hydrocarbonaceous charge stock which comprises: introducing said charge stock into an annular reaction zone defined by an outer wall and a below specified inner core maintained under superatmospheric pressure; maintaining within said reaction zone a mass of copper phthalocyanine catalyst disposed in a hollow core having a perforated wall; introducing molecular hydrogen into said core and therein contacting it with said catalyst at conditions selected to produce activated hydrogen and including a pressure of 1,000 to 3,000 psig and higher than said first mentioned pressure to preclude said charge stock from contacting the catalyst; and flowing the resultant activated hydrogen through said perforated wall into said reaction zone and reacting said charge stock therewith at thermal cracking conditions, including a temperature of 500* F. to 800* F.
 4. The process of claim 13 further characterized in that the conditions selected to produce activated hydrogen include a temperature above about 800* F. 